The objective of this training grant is to train biostatisticians to work in interdisciplinary collaborative teams addressing the problems associated with explaining the effects of chemical mixtures or in the area of toxicogenomics. A key to the success of this venture is the joining of the efforts of key scientists (genomic or mixtures toxicologists, risk assessors, environmental epidemiologists and biostatisticians) in the fileds of chemical mixtures or toxicognemoics with trainees from a Department Of Biostatistics. The goal is for trainees to gain an understanding of and experience working on statistical issues for two important areas of toxicology: mixtures toxicology and toxicogenomics. These trainees will be qualified to hold unique positions in governmental agencies, academia, and industry where properly evaluating risks associated with relevant chemical exposures is becoming increasingly important. The trainees will be Ph.D. students or postdoctoral students in the Department of Biostatistics at the Medical College of Virginia campus of Virginia Commonwealth University (VCD), where they will pursue pre- or postdoctoral training in the discipline of biostatistics. Additional expertise will be achieved through work on dissertation/research topics that are pertinent to the field of mixtures or toxicogenomics and through collaborative work with toxicologists and/or risk assessors actively working in the area of interest. Through these research projects, students will gain experience collaborating with a team of experts working on studies involving chemical mixtures or toxicogenomics. The trainees will assist in the design of studies, conduct appropriate power analyses, analyze resulting data, write reports for the preceptor with proper interpretation of the results, and participate in a collaborative team to produce one or more manuscripts for peer-review publication. In addition, the trainees will collaborate with biostatisticians who are developing statistical methodology for issues involved in the design and analysis of data resulting from chemical mixture studies or microarray studies. BACKGROUND This proposal reflects a continuation of an ongoing and unique training program on statistical methods for the toxicology of chemical mixtures. The proposed program incorporates a new and additional emphasis on toxicogenomics of mixtures. The proposal also adds a postdoctoral position to the program, supplementing the current five pre-doctoral trainees.